Most consumers want their hot beverages to be served just that way; hot. However, coffee and other hot beverages are often served by vendors at temperatures sufficiently high to cause severe discomfort or even burns, if the vendor and/or consumer does not take suitable precautions. For economic reasons, disposable hot beverage cups are typically made of light paper board or relatively thin foam wall construction, providing minimal thermal protection to the user's grip. A variety of available lid designs offers the vendor some choices as to what total container system best serves both the vendor's interest and the consumer's desire.
Most contemporary disposable lids are constructed as a thin wall, molded plastic structure sized for a press fit onto the top of standard size cups. Some lids provide additional structure elements such as ridges, vent holes, and openings through which the coffee or hot beverage can be consumed without being removed. Some lid designs have incorporated folding side tabs intended to provide thermal protection for the user's grip and/or to lock the lid on by gripping the rim or bead that terminates the top edge of the cup wall.
However, most users are forced to resort to using trays, double cups, fluted insulating booties or wraps sometimes referred to as "Java Jackets", bags, or to gripping the cup and lid by the bottom flange and edge of lid with minimal contact area and pressure, in order to avoid being burned. Also, the double cup and java jacket solutions add significant extra cost to the container component of the vendor's cost.
The prior patent art of disposable hot beverage cups and lids provides further context for the introduction of the invention, illustrating the efforts other inventors have made to deal with the problem. In particular, Smith's U.S. Pat. No. 5,348,181 discloses a disposable lid for hot beverage cups, that incorporates opposing side folding tabs that work off a snap/fold hinge mechanism to fold a centerline vertical bead molded into the tab into contact with the wall of the cup, locking the lid to the cup rim in the process. The area of contact of the tab with the cup wall is minimal, being a single line, and clearly should minimize the rate conduction of heat directly from the cup wall into the tab.
However, the geometry of the Smith tab hinge and others like it leaves an excessively protruding structure at each tab. The hinge structure in the tabs down position extends sufficiently far out outward from the edge of the lid to cause a problem in packing and carriage of cups capped with such lids. It is most noticeable when using trays or bags to carry more than one cup. It increases the likelihood of an inadvertent catching of the extending hinge structure by hand or other objects being moved, which could uncap and/or overturn the cup.
A further problem with the Smith tab is the possible deformation of the cup wall by gripping pressure of the user, due to the thin, lineal pattern of wall contact. This poses a risk of rupture or spillage due to constricted volume. Clearly, there is room for improvement in tabbed lid designs.